In the printing of sheets of paper or similar materials using printing machines, the correct positioning print of the printing image on the sheet is of considerable importance. This characteristic is designated by the term “registerability”. To determine the registerability, register marks are applied in addition to the printed image, whose deviations from the correctly positioned printing are determined and measured by the operator of the printing machine. Due to an improvement in this method, the registerability is automatically determined and calculated by sensors in the printing machine. To this end, the sensors record the register marks on the sheet and, by the measured position of the register mark and a target position, determine whether or not the printing is taking place correctly. In case of register deviations or register errors, the printing machine is instructed accordingly in order to correct them. The disadvantage of the state-of-the-art method is that under the same conditions, register marks are applied undesirably at different locations with various types of printing materials. For example, if a thick print substrate is used, the register marks are applied at a marginally different location than if a thin print substrate is used. Such errors are regularly corrected, whereby the availability of the printing machine is diminished by the correction measures that are usually carried out with special calibration runs. Another disadvantage with the state-of-the-art method described is the high number of detection components. In addition, with the state-of-the-art method described, each sheet is stopped to check its alignment, which takes a considerable amount of time.